Sleep apnea is a potentially life-threatening breathing disorder characterized by brief interruptions of breathing during sleep. There are two types of sleep apnea; central and obstructive. Central sleep apnea, which is less common, occurs when the brain fails to send appropriate signals to breathing muscles to initiate ventilation. Obstructive sleep apnea (OSA) occurs when air cannot flow into or out of the person's nose or mouth although the efforts to breathe continue. In a given night, the number of involuntary breathing pauses as measured by the Apnea-Hypopnea Index (AHI) may exceed 30, which is considered to be severe OSA. Early recognition and treatment of sleep apnea is important because it may be associated with irregular heartbeat, high blood pressure, heart attack, stroke and other co-morbid medical conditions. The estimated prevalence of OSA is 2% of women and 4% of men between the ages of 40-65. It is estimated that up to 80% of patients remain undiagnosed.
Continuous Positive Airway Pressure (CPAP) therapy is the gold standard for the treatment of OSA. However, despite the known efficacy of CPAP therapy, it is estimated that 46-83% of patients are nonadherent.
Nasal Expiratory Positive Airway Pressure (EPAP) is a viable FDA approved treatment of OSA. EPAP is effective in reducing AHI and improving subjective daytime sleepiness. It has been shown to improve tolerability and long term compliance.
A currently approved and marketed EPAP device consists of a pair of valves fixed to the nares with adhesive disks. The valves are disposable and are approved for one night of use only. The cost of continuous replacement, as well as some complaints of irritation caused by the adhesive, has limited the use of this therapy.
Further, some have complained of some restriction to inspiration because of the small surface area of the flap valve.